Image reading apparatuses included in copiers, scanners, and multifunction apparatus having a copy function and a scanning function, contain automatic document feeders (“ADF”) to feed documents from an input tray through a feed path to an output tray. In addition, in order to read a document printed on a first surface and a second surface, known document feeders that feed a document for double-sided reading by reversing the document's leading end and trailing end.
FIG. 16 shows a feed path in a conventional document feeder capable of double-sided reading. As shown in the figure, a document P is placed on an input tray 90 with a first surface (a first page) facing upward. This document P is fed to a feed path 92 by a pickup roller 91. In the feed path 92, the document P is fed by feed rollers 93 provided as appropriate, and the first surface of the document P is read by an image reading device, such as CCD or CIS, when the document P passes a reading position X. When a sensor detects a trailing end of the document P, of which the first surface has been read, ejection rollers 94 are stopped with the trailing end of the document P nipped. As the ejection rollers 94 are rotated backward, the document P is fed to a switchback path 95. The document P goes from the switchback path 95 toward an upstream side of the reading position X of the feed path 92. As a result, the leading end and the trailing end of the document P are reversed, and the document P is inverted.
Then, the document P is fed by the feed rollers 93, and the second surface of the document P is read by the image reading device when the document P passes the reading position X. When a sensor detects the trailing end of the document P, of which the second surface now has been read, the ejection rollers 94 are stopped again with the trailing end of the document P nipped, and then the document P is fed back to the switchback path 95. When the document P enters the feed path 92 again from the switchback path 95, its leading end and trailing end are reversed again, that is, the first surface faces the reading position X, and the document P is again inverted. The document P then is fed on the feed path 92 and ejected to an output tray 96 with its first surface facing downward. Thus, the first and second surfaces of the document P are read, and the document P is ejected to the output tray 96 in the same sequence as the original documents P, in the original order, placed on the input tray 90.
In the above automatic document feeder, the feed path 92 is designed to be opened to remove a jammed document P. For example, by opening an upper cover of the housing of the automatic document feeder in which the feed path 92 is formed, an outer guide surface, which defines an upper portion of the feed path 92, is also opened, so that the upper portion of the feed path 92 is released. Thus, a document jam in the upper portion of the feed path 92 can be cleared.
During double-sided reading of a document P fed by the existing automatic document feeder, a document jam may occur in the switchback path 95. To clear the document jam in the switchback path 95, a structural member forming an inner guide surface, which deforms the upper portion of the feed path 92, and the upper guide surface of the switchback path 95 is designed to rotate. By opening the upper cover of the apparatus housing and then rotating the member, the switchback path 95 is released. Thus, a document jam in the switchback path 95 can be cleared.
In conventional automatic document feeders, such as described above, clearing jams in feed path 92 is a different operation than clearing jams in switchback path 95, and a user needs to open the upper cover, and rotate a different member according to where the paper jam occurred. However, when a document P is jammed, the user typically does not know where the paper jam has occurred. Thus, the user needs to open the upper cover and test the various rotatable members until the jammed document P is found.
Sensors for detecting the presence or absence of the document P may be disposed in the feed path 92 and the switchback path 95 to sense the position of the jammed document. The sensors may be connected to a display to inform the user. However, even with sensors, when a jam occurs in the switchback path 95, it is generally not enough to open the upper cover to clear the jam. As discussed above, members may need to be rotated thus requiring a mechanism to rotate the members.